1. Field of the Invention
This invention relates generally to oral compositions for enhancing oral hygiene, and more particularly, to enzyme containing oral compositions having enhanced stability and antiplaque effectiveness.
2. The Prior Art
Oral compositions such as toothpastes, gels and mouth washes are designed to loosen and remove plaque in conjunction with a regular toothbrushing regimen. Dental plaque is present to some degree, in the form of a film, on virtually all dental surfaces. It is a byproduct of microbial growth, and comprises a dense microbial layer consisting of a mass of microorganisms embedded in a polysaccharide matrix. Plaque itself adheres firmly to dental surfaces and is removed only with difficulty even through a rigorous brushing regimen. Moreover, plaque rapidly reforms on the tooth surface after it is removed. Plaque may form on any part of the tooth surface, and is found particularly at the gingival margin, in cracks in the enamel, and on the surface of dental calculus. The danger associated with the formation of plaque on the teeth lies in the tendency of plaque to build up and eventually produce gingivitis, periodontitis and other types of periodontal disease, as well as dental caries and dental calculus.
It is known to the art to incorporate antimicrobial agents in oral compositions wherein these agents destroy or inhibit oral bacteria. Other agents are also incorporated in the oral composition to enhance the efficacy of the antimicrobial agents. For example, it is known to incorporate enzymes such as proteases in oral compositions, which enzymes disrupt or interfere with plaque formation and bacterial adhesion to tooth surfaces.
A problem encountered with commercially processed enzymes such as proteases is that they often contain a broad spectrum of undesirable by-products or impurities that are difficult to remove during manufacture. One such enzyme by-product is cellulase, an enzyme that catabolizes cellulose to simple sugars by hydrolysis of β (1–4) linkages.
Thickening agents conventionally used in oral compositions such as carboxymethyl cellulose, undergo degradation in the presence of cellulase enzymes which detrimentally affects the rheology of the dentifrice product. Thus, a means to inhibit the degradation of these thickeners by cellulase is a critical to obtaining stable enzyme containing oral care formulations.
Typical methods employed by the art for cellulase inhibition or isolation are not practical for use in the oral composition field. Treatments for cellulase inhibition such as salting out, heat treatment, or pH adjustment also compromise the activity of the enzymes. Classical methods of enzyme separation based on enzyme size, charge, solubility, and binding site are cost prohibitive and ineffective due to the similarities between certain cellulases and enzymes such as amylases. Inhibition of cellulase activity by treatment with heavy metals or heavy metal complexes such as mercury, silver and palladium chloride that bind to the enzyme active site are also unacceptable as these materials are toxic to humans and certainly cannot be used in an oral care product.